Bone Abstracts

Objectives: Type V osteogenesis imperfecta (OI) results in abnormal modelling of the ulna, dislocation of the radial head and interosseous membrane calcification (IOM). Individuals develop reduced functional ability as a consequence of reduced range of movement (ROM) including elbow flexion and/or supination, which may be intrinsic or secondary to the radiographic findings. We describe the evolution of radiographic and functional parameters in a cohort seen in our centre.

Method: We performed a retrospective review of all type V OI cases seen in our institution. ROM data included earliest loss of elbow flexion (≤120°) and supination (≤60°). Radiographic images were double reported, consensus reached in cases of discrepancy. Earliest age of onset was determined for radiographic features: IOM; subluxation (SUBL) or complete dislocation (DISL) of radial head; abnormal modelling of proximal ulna (ULNMd); and ulna bowing ≥15° (UBOW15).

Results: Thirteen cases were reviewed (6 male/7 female; mean age 6.5 years (0.3–16.8 years)). ROM and radiographic data were available in 12/13 and 10/13, respectively; both available in 9/13. Loss of flexion and supination occurred in 12 elbows (6/12 children) and 14 elbows (8/12 children), respectively. Mean ages of loss of flexion and supination were 2.9 years and 4.6 years, respectively. Of those >2.9 years, 4/7 had flexion loss. Of those >4.6 years 6/7 had supination loss. Evolution of supination loss was variable over time. In contrast, flexion loss progressed steadily over time. In none of those with flexion ≤120°, was there recovery to normal. The pattern of evolution of both flexion and supination was remarkably symmetrical within individuals. Mean age (proportion of cases; range) at which radiographic features appeared were: IOM 4.1 years (7/10;0.1–12.4 years); SUBL 3.6yrs (4/10;1.8–5.2 years); DISL 5.5 years (4/10;3.2–6.9 years); ULNMd 4.2 years (7/10;0.7–12.5 years); UBOW15 2.4 years (3/10;1.5–2.9 years). Development of radiographic changes was not symmetrical within individuals.

Conclusion: We present data detailing the natural history of ROM and radiographic changes in the forearm in type V OI. We did not find a close relationship between loss of ROM and radiographic changes in the forearm and elbow. The symmetry of changes in ROM within individuals with type V OI suggests that these are partially due to intrinsic/systemic factors but not radiographic findings.

Disclosure: The authors declared no competing interests.